In a mixed coverage area of 1XRTT and 1XEV-DO, it is very possible for carriers to deploy separate PDSN/AAA to manage each wireless network separately. Because of the separate management, it is possible for carriers to control data access (i.e. establish a PPP session) to each network with separate mobile authentication rules.
An EVDO capable device, when queried about Protocol Capability for Over The Air Provisioning, it will inform the network that it is capable of IS-683C version of PRL. Network therefore can download an IS-683C version of PRL but it is possible that user may not purchase EVDO service. Under such circumstances, device SW is unaware of such service unavailability and therefore will always try to perform any data access through the EVDO network. The EVDO standard already has the provision for AN level authentication, which is an optional feature that a carrier may or may not be implemented.
For scenarios where AN Authentication is disabled but PDSN/AAA authentication is separate between EVDO & 1X network, there needs to be a mechanism for a device with EVDO PRL but not configured by network for EVDO service to fall back to 1X system for data service; this behaviour is currently undefined.
Also, if the user later on purchases EVDO service, there needs to be a seamless mechanism for the device to resume from 1X fall back condition to start using the EVDO service without the need to reconfigure anything on the device—this behaviour is also not defined any where.
Hence there is a need for an improved data access method and apparatus for mobile terminal.